1. Field of the Invention
This invention relates to a cable spraying apparatus for spraying insulating and coating material on cables and more particularly overhead cables which are supported by intervally spaced connectors which suspend the cable under an overhead supportive wire.
2. Description of the Prior Art
Thousands of miles of overhead cables have been installed on utility poles and telephone poles for the transmission of electric current. Many of these cables are desirably insulated for higher efficiency or for safety. These cables are in constant use for a period of many years. After a period of time the original coating becomes cracked, worn out, or develops a plurality of tiny pin holes, leaving the conductive cable exposed to the natural elements. Many miles of the original coating comprise a lead wrapper about the cable. The lead wrapper is particularly prone to develop a plurality of pin holes therethrough leaving the cable exposed. The cable must be recoated before the natural elements corrode and break the cable which stops the flow of electricity.
Because the overhead cables are many feet above the ground, particular problems are encountered with recoating the cables. It is uneconomical and dangerous to elevate a person by hoist to spray or brush coating material onto the cable. Consequently, a device must remotely apply a coating onto the cable.
Certain apparatus have already been developed to solve some of the problems with recoating overhead cables. One device is disclosed in U.S. Pat. No. 1,269,514 issued to Ulrich on June 11, 1918. Ulrich discloses an insulation repairing device comprising a receptacle containing heated and liquified coating material. A cover to the receptacle has trolley wheels mounted thereon for engagement with the cable. A roller is spring mounted on the receptacle. The roller comprises a pair of discs with bristles pointing upwardly. The cable passes through the bristles forcing the roller to rotate, dipping the bristles into the liquified coating material and brushing the material onto the cable.
U.S. Pat. No. 632,654 issued to Lewis on Sept. 5, 1899, discloses an insulating apparatus mounted atop a pole. The apparatus has a receptacle for liquified coating material. A pulley has a belt dipping into the receptacle and moving upward and entrained around a top pulley. The top pulley has a blade which transfers the liquid coating onto a serrated wheel which rests on the cable. The serrated wheel transfers the coating onto the cable. A spongeous mop is mounted to the receptacle and engages the underside of the cable to wipe off excess coating.
U.S. Pat. No. 2,253,019 issued to Crepeau on Aug. 19, 1974, discloses a pump spray device mounted atop a pole. An operator has a wagon mounting the supply tank of coating material and the pump. Conduit hoses lead from the wagon up a pole to the spraying apparatus. The spraying apparatus is mounted on a supportive wire by two trolley wheels. Two top nozzles point downwardly onto the cable and the bottom nozzle points upwardly to the cable. The nozzles are operably connected to the hoses. The top nozzles are manually adjustable to a desired distance from the cable.
U.S. Pat. No. 2,264,048 issued to McMahon et al on Nov. 25, 1941, discloses a self-propelled apparatus. Downwardly extending tubular nozzles are on both sides of the cable. The tubular nozzles are pivotably mounted by L and T joints to allow the nozzles to pivot out of the way of interferring telephone or utility poles and pivot back to their free position when they pass the utility pole. In this fashion the self-propelled apparatus can continually spray the cable without interruption from the spaced supporting poles.
Two problems are encountered with spraying thick tar-like coating material on overhead cables. First, it is difficult to control the amount and uniformity of the coating sprayed onto the cable. Second, the amount of spray which is put on the cable is a small portion of the total amount of spray exiting from the nozzle. The excess or divergent spray results in much waste.
As to the first problem, often the amount sprayed is too little to effectively coat the cable or it is too much, which causes excessive dripping and a waste of material. There are two factors causing one portion of the cable to receive too little coating while another portion receives too much. One factor is that the cable is not uniformly suspended from its supportive wire. Rings which are attached to the wire and through which the cable extends and is supported thereby are different sizes. The cable rises and dips from ring to ring depending on the size of the successive rings.
The second factor is that the density of the spray varies inversely with the distance between the cable and the nozzle. As such, when the nozzles of the spraying apparatus become too far away, the spray becomes too thin, and when the nozzles become too close to the cable, the spray becomes excessive. As to the second problem, a shield or container is needed to substantially surround the nozzles to retain and recycle divergent spray. However, a container would normally interfere with the remote mounting and dismounting of the apparatus with the supportive wire.
One of the objects of the present invention is to provide an improved cable coating apparatus that provides an even and consistent coating on a cable even though the cable may hang at different distances from the supporting wire.
Another object of present invention is to provide a cable coating apparatus that collects and recycles excess coating material, yet does not interfere with the remote mounting and dismounting of the apparatus on the supporting wire.